Concepts are highly theoretical entities. One cannot study
them empirically without committing oneself to substantial preliminary
assumptions. Among the competing theories of concepts and
categorization developed by psychologists in the last thirty years,
the implicit theoretical assumption that what falls under a concept is
determined by description (“descriptionism”) has never
been seriously challenged. I present a nondescriptionist theory of our
most basic concepts, “substances,” which include (1)
stuffs (gold, milk), (2) real kinds (cat, chair), and (3) individuals
(Mama, Bill Clinton, the Empire State Building). On the basis of
something important that all three have in common, our earliest and
most basic concepts of substances are identical in structure. The
membership of the category “cat,” like that of
“Mama,” is a natural unit in nature, to which the concept
“cat” does something like pointing, and continues to point
despite large changes in the properties the thinker represents the
unit as having. For example, large changes can occur in the way a
child identifies cats and the things it is willing to call
“cat” without affecting the extension of its word
“cat.” The difficulty is to cash in the metaphor of
“pointing” in this context. Having substance concepts need
not depend on knowing words, but language interacts with substance
concepts, completely transforming the conceptual repertoire. I will
discuss how public language plays a crucial role in both the
acquisition of substance concepts and their completed
structure.